Leak resistant tamper evident reclosable plastic bag

ABSTRACT

A reclosable plastic bag includes lips that are adjacent to the opening near the top of the bag and which are initially joined to one another by a removable element. The removable element when attached indicates that the bag has not yet been used. When the removable element is no longer attached this indicates that the bag may have been opened and the contents contaminated. The reclosable plastic bag also includes a closure element for sealing and unsealing the top of the bag that incorporates two substantially parallel, but spaced apart, zippers. This combination of two zippers and the spacing between them reduces the likelihood that the closure will leak or inadvertently open.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/093,565, filed Mar. 8, 2002, which is incorporated in thisapplication in its entirety by this reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to containers and morespecifically to reclosable plastic bags.

Reclosable plastic bags are used for many purposes, includingtransporting and storing food products and other materials. Reclosablebags are often preferred over other available bags because of numerousadvantages, including that they are easy to close and reopen for accesswithout compromise of integrity when closed.

Typically, such bags are reclosable using a zip-action, lockingreclosable closure. Unfortunately, when using such a bag for a firsttime, there is currently no way of knowing if the bag is sanitary, hasbeen used, tampered with or otherwise contaminated. This is particularlyimportant if the contents to be stored in the bag are perishable oreasily contaminated. Exemplary of such is breast milk.

Likewise, currently available bags are typically difficult to fill(E.G., with a liquid substance) without obstruction from the lips and/orspilling along the sides of the bag. At least one reason it is difficultto fill currently available bags is that the edges are typicallyheat-sealed along their entire length from the bottom of the bag to thetop of the bag. These heat-sealed edges typically make it somewhatdifficult to pull the lips apart, as well as impede the ability of thebag to remain open during filling.

Yet another disadvantage of using currently available bags to storeliquids is that the zipper may not remain sealed. This is particularlytrue when, for instance, the bag lies on its side—the bag thus situatedis more likely to seep some of the liquid contents.

The present invention avoids these and other difficulties by providing atamper evident reclosable bag that ensures that the bag is being usedfor the first time. The present invention further provides a bag that iseasier to open, easier to fill, seals better, and has less leakage thancurrently available bags.

SUMMARY OF THE INVENTION

Briefly described, in a first preferred form the present inventioncomprises a reclosable plastic bag. The reclosable plastic bag of thepresent invention has many uses; one exemplary use of the bag is forstoring liquids, such as breast milk. The bag of the present inventionincludes two panels sealed to form a container having a bottom and anopenable top. The plastic bag further includes lips that are adjacent tothe openable top and which are initially joined to one another by aremovable element. The removable element when attached indicates thatthe bag has not yet been used. When the removable element is no longerattached this indicates that the bag may have been used (and potentiallycontaminated). The reclosable plastic bag also includes a closureelement for sealing and unsealing the openable top of the bag.

Optionally, the lips are unattached to one another along a significantportion of their respective side edges, but are attached to one anotherfor at least a little length along the side edges immediately above theclosure element. Optionally, this can be accomplished by initiallysealing the lips to one another using a heat seal along the side edgesand then notching the side edges of the lips to remove at least part ofthe heat seal.

Also optionally, the lips can be scored or otherwise pre-formed forfacilitating removal of the removable element. Also optionally, the lipscan include indicia (markings) to indicate the location of the removableelement.

Furthermore, the reclosable plastic bag of the present invention caninclude two closure elements to provide a more leak-proof sealing of thebag. Most preferably, the two zippers each include an asymmetrical barb,which barbs are both oriented in a manner to facilitate opening the bagusing the lips but rendering accidental opening of the bag less likely.Preferably, each of the lips is rather tall to facilitate easy openingof the bag. Most preferably, each of the lips is more than one inch inheight.

In another preferred form, the present invention comprises a reclosableplastic bag including front and back panels sealed to one another toform a container. The container has a bottom, an openable top and aclosure element for sealing and unsealing the openable top. Lips extendfrom the closure element for facilitating the opening of the closureelement. The lips are sealed to one another along their respective sideedges immediately above the closure element, but are unattached to oneanother along a substantial portion of their side edges.

Preferably, the lips are unattached to one another along most of theirrespective side edges. Optionally, the lips are notched along theirrespective side edges to remove a heat seam initially formed in the sideedges. Optionally, each of the lips is more than one inch in height tofacilitate easy opening of the bag.

Preferably, the bag includes two closure elements, one parallel to theother. Preferably, each of these closure elements includes anasymmetrical barb having a long side and a short side, with the longsides of the barbs pointing toward the interior of the bag and away fromthe lips. Preferably, the bottom of the bag is gusseted to enable thebag to be freestanding.

Optionally, the lips are initially joined to one another by a removablestrip, the removable strip when attached indicating that the bag has notbeen used and when no longer attached indicating that the bag might havebeen used. Optionally, the lips can be scored or otherwise pre-formed tofacilitate easy removal of the removable strip.

Bags according to the present invention have numerous advantages. Forexample, such a bag is extremely well-suited to containing liquids andaggregate material. Furthermore, it is particularly well-suited tosafely storing perishables, including breast milk, for example.Contributing to this utility is the ability to ensure that the interiorof the bag has not been contaminated simply by observing that thetamper-evident strip or removable element is still attached to the lips(i.e., the lips are still attached to one another). This is a goodindication that the bag has not been opened and thereby indicates thatno contamination has been introduced into the interior of the bag.Moreover, the large lips provide more convenient handles for handlingthe bag and opening the openable top of the bag. The cutouts in the lipsprovide a ready grip even when the lips are still joined by theremovable strip. Furthermore, by eliminating some of the heat sealnormally found on typical prior art reclosable plastic bags along theentire length of the side edges of the lips, the lips are more naturallyopened, ready to pull part.

Also, by providing some heat seal along the side edges of the lipsimmediately above the zipper, the integrity of the edge of the zipper isprotected as the user pulls on the lips. In other words, without atleast a little heat seal above the zipper (or some other strain relieffeature), pulling on the lips would tend to pull the edges of the zipperapart. Furthermore, the use of dual, asymmetrical zippers helps toensure that the contents of the bag do not leak out. The bottom gussetallows the bag to be freestanding, an important advantage when dealingwith liquid contents.

That the invention improves over the prior art and accomplishes theadvantages described above will become apparent from the followingdetailed description of the exemplary embodiments and the appendeddrawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

As used herein, like numerals throughout the various figures representthe same or equivalent features of the present invention.

FIG. 1 is a front perspective view of a tamper evident reclosableplastic bag according to one aspect of the present invention.

FIG. 2 is a fragmentary cross-sectional view of a portion of the bag ofFIG. 1 including a closure element according to one aspect of thepresent invention.

FIG. 3 is a front perspective view of the bag of FIG. 1 shown bearingindicia and containing a liquid according to one aspect of the presentinvention.

FIG. 4 is a front view of a tamper evident reclosable plastic bagaccording to a second preferred form of the invention, the bag includingmultiple closure elements.

FIG. 5 is a schematic, plan view of bag film as it is being formed intobags according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention is directed to containers and in particular tonovel reclosable plastic bags, tamper evident plastic bags, and closureprofiles for reclosable bags. The general principles for makingreclosable plastic bags are fairly well-known and are typified innumerous prior patents. Various developments in the reclosable plasticbag art, including methods of manufacture and various die assembliesused to manufacture such bags, are disclosed in U.S. Pat. No. 6,217,216to Taheri (describes methods for forming bags), U.S. Pat. No. 4,755,248to Geiser et al. (die assemblies), U.S. Pat. Nos. 4,101,355 (usingadhesives to join a closure profile to a bag) and 3,338,284 (forming abag film web using a single extrusion operation) to Ausnit, U.S. Pat.Nos. Re. 28,959, 29,208 and 28,969 to Naito, U.S. Pat. No. Re. 33,674 toUramoto, and U.S. Pat. No. Re. 26,991 to Luca, (interlocking closureprofiles), all of which are hereby incorporated by reference in theirentireties for background information. Although these patents disclosenumerous fundamental methods for forming reclosable bags and reclosableclosure elements, the present improvements are intended to be suitablewith any of the known methods. It may be possible to use manyfundamental methods, to modify or adapt them, and to incorporate theminto the invention disclosed below.

In a first preferred form the present invention comprises a reclosablebag 10, as shown for instance in FIG. 1, and includes first and secondpanels 12 and 13. As contemplated herein, bag 10 can contain more thantwo panels, such as when a third panel is provided to form a documentpouch for holding papers or identifying material (not shown).

The bag 10 preferably is fabricated from plastic or other flexiblematerial(s). The bag 10 can be formed from one or more of the followingsuitable materials, including but not limited to, polyethylene, lowdensity polyethylene (LDPE), linear low density polyethylene (LLDPE),polypropylene, ethyl vinyl acetate (EVA), or other suitable polymericmaterials. It is specifically contemplated herein that a combination ofEVA, LDPE and LLDPE would provide an advantageous material from which toform the bag. More specifically, it is believed that a combination ofabout 10% EVA, about 30% LLDPE, and about 60% LDPE provides a bag havingthe most desirable properties, including pliability, a lower degree ofbrittleness (particularly at cold temperatures), and the like. Further,although typical bag thickness would be apparent to those of ordinaryskill in the art, the preferred bag according to the present inventionwill have a thickness of about 2.5-3 mils.

Still referring to FIG. 1, each of the first and second panels 12 and 13extend to and form a bottom or bottom edge 16, side edges 24, 25, anopenable top 18, and first and second lips 19 and 22. The panels 12 and13 are joined or sealed to one another to define a container having aninterior or interior region capable of receiving and storing contents.

As contemplated herein, the lips 19 and 22 extend substantially aboveand from the closure element 30 in a way that facilitates easy openingof the bag 10. To that end, the lips preferably extend more than oneinch in height above the closure element 30 (most preferably about twoinches in height). During manufacture of the bag 10, the side edges orseals 24, 25 typically extend from the openable top 18 to the bottom 16and the lips are initially sealed to one another along these side edges.To facilitate opening of the bag 10, a portion of the side edge adjacentthe lips 19 and 22 can be notched or otherwise unattached to each otherin regions 23, 23 a. Preferably, at least a portion of the side edges ofthe lips remains attached to one another immediately above the closureelement 30, thereby providing additional strain relief, and theunattached regions 23, 23 a extend along a majority portion of the sideedges of the lips.

According to the present invention and as best seen in FIG. 2, aremovable element 20 is included which provides evidence of tampering orpotential contamination prior to use of the bag 10. When the removableelement 20 remains attached to the bag 10, it is indicative that the baghas not yet been used. In other words, in order to actually open thebag, normally the removable element 20 must first be removed. Once theremovable element 20 is removed, it is indicative that the bag may havebeen used. The removable element 20 can be formed by creating an area onthe lips 19 and 22 of reduced strength or thickness, such an area beingpositioned between the openable top 18 and the closure element 30 andshown generally at 20 a and 20 b. Exemplary of a method for forming theremovable element 20 includes scoring or perforating the lips orotherwise pre-forming the lips to facilitate removal of the removableelement. This can include creating a section of reduced thicknessrelative to the adjacent regions in each of the first and second panels12 and 13.

The lips can also include gripper lines, such as gripper lines 61 and62. Although eight such gripper lines are depicted in FIG. 2, thoseskilled in the art will recognize that fewer or more gripper lines canbe employed. Furthermore, the gripper lines can be eliminatedaltogether. However, the gripper lines are helpful for providing a moresure grasp of the lips for opening of the bag and it is preferred thatthey be provided.

The openable top 18 communicates with the interior of the bag 10, andprovides an avenue by which contents 14 can be placed within or removedfrom the bag (once the removable element 20 is removed). Once thecontents 14 are placed in the bag 10, the bottom 16 spreads using thegusset 17, and the bag is rendered freestanding when filled.Additionally, the lips 19 and 22 are positioned adjacent the openabletop 18 and initially joined to one another by the removable element 20.

FIG. 2 illustrates a fragmentary cross-sectional view of a portion ofbag 10. According to one aspect of the present invention, the closureelement 30 is provided on at least a portion of the at least one panels12 and 13, and can be, for example, a zip-type closure. The closureelement 30 is typically adapted to be releasably engageable, therebybeing capable of sealing and unsealing. The closure forms a hermeticseal preventing entry of contaminants into the interior region and/orpreventing inadvertent discharge from the interior region. The closureelement may be formed on, formed within or attached to the panels. Inother words, the closure element can be formed integral with the panel,(such as by extrusion), or separately formed and attached or fused ontothe panels after the bag film web is extruded. Such attachment meansinclude but are not limited to adhesive attachment, welding, or otherattachment means. In alternative embodiments, the closure can includeother types of releasable closures such as releasable adhesive, or evennon-releasable closures such as non-releasable adhesive.

A typical closure element 30 is depicted and includes a male element 32and female element 34, both of which are designed and shaped to beinterlocking in such a manner that the bag 10 can be opened from theoutside, while resisting opening from the pressures created by thecontents of the bag. The male element 32, can further contain one ormore structural rib(s) 36 so as to increase the structural integrity andsealing ability of the closure profile. It will likewise be understoodthat it is within the scope of the present invention that the maleelement 32 can be attached to the second panel 13 and the female element34 can be attached to the first panel 12.

Preferably, as shown herein, the male element 32 includes anasymmetrical barb such that the portion of the barb that is orientedtowards the contents of the bag 10 is larger (longer) than the portionof the barb oriented away from the contents. Such an arrangementfacilitates intentional opening of the lips, while rendering accidentalopening (resulting in seepage or spilling of the contents) of the bagless likely.

If desired, various parts of the bag can be formed with strips ofdifferent colors. For instance, the male element 32 could be made as ablue strip, while the female element 34 could be made of a red strip.Further, it is also contemplated that any portion of the bag couldcontain indicia, such as a printed or embossed design. If situated onthe lips, the indicia could indicate the location of the removableelement 21 (see, for instance, FIG. 4). Provision of indicia of anintricate, regular pattern, such as for example a bulls-eye pattern orcross-hatching, will more readily indicate tampering. As shown in FIG.3, additional indicia could include quantity markings, identificationmarkings, and the like.

Using an appropriate method for forming plastic bags, the presentinvention can be made from a bag film web. The bag 10 can be extrudedthrough a die assembly as a tubular web. It is possible to extrude theweb, fold it accordingly, then perform various operations on the foldedweb to create individual bags. For instance, once the bag film web hasbeen formed into a tube, it can then be rolled onto a spool and fed intoan apparatus designed for making bags from bag film web (not shown). Onetype of a bag making apparatus involves the use of a hot knife that cutsthe bag and seals the bag to create the side edges or seals 24, 25thereby forming a heat seam along the side edges.

To manufacture bags according to the present invention, the followingmanufacturing steps can be carried out. Firstly, a roll of stock of bagmaking film (reclosable bag making material) with a specific size andlength is chosen (or fabricated). Secondly, a perforation line orscoring is put on the lip of the bag at the time the roll stock ismoving on the conveyor of the bag making machine. The lip is not cutcompletely therethrough and therefore is not separated at this time.Thirdly, a hole punch is used to punch holes in the lips at apredetermined spacing equal to the desired width of the bag. Fourthly, ahot knife is used to cut the bags to length and to heat seal the sides.

Bags according to the present invention have numerous advantages. Forexample, such a bag is extremely well-suited to containing liquids andaggregate material. Furthermore, it is particularly well-suited tosafely storing breast milk, for example. Contributing to this utility isthe ability to ensure that the interior of the bag has not beencontaminated simply by observing that the tamper-evident strip orremovable element is still attached to the lips (i.e., the lips arestill attached to one another). This is a good indication that the baghas not been opened and thereby indicates that no contamination has beenintroduced into the interior of the bag. Moreover, the large lipsprovide more convenient handles for handling the bag and opening theopenable top of the bag. The cutouts in the lips provide a ready gripeven when the lips are still joined by the removable strip. Furthermore,by eliminating some of the heat seal normally found on typical prior artreclosable plastic bags along the entire length of the side edges of thelips, the lips are more naturally opened, ready to pull part.

Also, by retaining some heat seal along the side edges of the lipsimmediately above the closure element, the integrity of the edge of theclosure element is protected as the user pulls on the lips. In otherwords, with at least a little heat seal above the closure element, theclosure element is protected from pulling on the lips otherwise wouldtend to pull the edges of the closure element apart.

As shown in FIG. 4, it is also possible according to the presentinvention that more than one closure element 30 can be utilized toensure that contents of the bag are not lost. As shown herein, primaryand secondary closure elements 30 are arranged and oriented parallel toone another, separated by a gap of about ¼ inch or so. Using such anarrangement, if one closure element fails, the secondary closure elementcan yet contain the contents.

In use, the removable element 20 is detached from the lips 19 and 22 ofthe bag 10. The lips are then separated, and the closure element 30 isopened to deposit contents 14 (e.g., breast milk) into the interiorregion of the bag 10 through the openable top 18. Additional contentscan be deposited, or deposited contents can be removed from the interiorregion by selectively opening and resealing the first and second closureelement 30.

If a small ultrasonic seal is applied to the ends of the closure 30,this tends to flatten out the high profile of the closure (the bumpinessof the profile). This facilitates the use of a substantially wider sideheat seam along the side edges of the bag, which can be advantageous forproviding a more leak-proof bag. The small ultrasonic seal typicallywould be on the order of 118 inch or less across.

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equivalentsof the features shown and described or portions thereof. Having thusdescribed the invention in detail, it should be apparent to thoseskilled in the art that various modifications can be made in the presentinvention without departing from the spirit and scope of the followingclaims.

1. A reclosable plastic bag, comprising: A. a first panel attached to asecond panel to form a container having a bottom and a sealed top edge;B. a primary closure located between the bottom and the sealed top edge,comprising: i. a primary female profile on the first panel of thecontainer, ii. a primary male profile on the second panel of thecontainer that is configured to engage selectively with the primaryfemale profile; C. a removable element of the container extending fromthe sealed top edge to a separation line located between the sealed topedge and the primary closure and that when still attached to thecontainer indicates that the container has not yet been opened; D. afirst lip portion of the first panel extending from the primary closureto the separation line and including a first right edge and a first leftedge; and E. a second lip portion of the second panel extending from theprimary closure to the separation line and including a second right edgeand a second left edge; in which: i. the first right edge is attached tothe second right edge from the primary closure to a right cutout portionof the first and second lip portions in which the first right edge isnot attached to the second right edge and ii. the first left edge isattached to the second left edge from the primary closure to a leftcutout portion of the first and second lip portions in which the firstleft edge is not attached to the second left edge.